HOIS Highlights 2023-2024
Inspection of Socket Weld Fittings
Background
Socket weld fittings, commonly manufactured from carbon steel and both austenitic and duplex stainless steels, are used in instrumentation points, vents, and drains. One of the most common failure mechanisms of socket weld assemblies is high cycle fatigue at the fillet welds that connect the socket weld fitting and the pipe. The formation and progression of fatigue cracking is exacerbated by the presence of vibration, the weight of the components and the presence of unsupported connections.
Typical inspection methods such as magnetic particle inspection, dye penetrant inspection, visual inspection, and sometimes digital radiography are claimed, by some, to not have a high probability of detection, especially with regard to cracks that have initiated at the weld root and are not surface breaking. As a result, this project aims to identify the current inspection methods used in service and techniques that have potential for this challenging problem.
The main objective of this project is to develop a recommended practice for the inspection of socket weld fittings. The guidance will be based on the results of a rigorously controlled blind trial programme and group member experience.
Progress Update
Three open samples were manufactured to determine whether the samples were suitable and to provide the trialists with an opportunity to refine their approach.
Following completion of the open trials, nine additional samples were manufactured which contained crack-like features at either the weld root or weld toe. Currently, three trialists have inspected the samples, CAN, Eddyfi and TesTex. The techniques used were PAUT (CAN & Eddyfi) and ‘Method X’ from TesTex which is and electromagnetic technique.
It is hoped that one more trial will be conducted on the blind samples, before completion of the trial report later in 2024.
Trial document will be issued later in 2024.